Ion implantation for treating a substrate is often performed using a beamline ion implanter, which may include various components to shape an ion beam and control ion beam energy and species. In order to control purity of species to be implanted into a substrate mass resolution may be performed by components that provide magnetic or electrostatic deflection in order to filter out ions of an unwanted species. However, beamline ion implanters occupy a large footprint that imparts a relatively large cost for treatment of ions using a beamline ion implanter.
Alternatives to beamline ion implanters include more compact apparatus such as plasma doping (PLAD) apparatus or plasma immersion apparatus, in which a plasma chamber or arc chamber from which ions are directed to a substrate is placed adjacent a substrate chamber or forms the substrate processing chamber itself. Such apparatus provide the advantage of a smaller footprint and have fewer optical components than a conventional beamline ion implanter.
However, in this type of apparatus and other PLAD type apparatus the throw distance through which ions travel from plasma to substrate may be on the order of millimeters or a few centimeters. Accordingly, it may not be practical to introduce components to perform mass resolution of ions produced by the plasma before the ions impact the substrate. Thus, in these compact apparatus substrates are treated with ions that are not mass analyzed and may therefore include unwanted ion species. Accordingly, in present day plasma or ion beam processing technology a tradeoff exists between purity of ions in an ion beam as afforded by a beamline ion implanter and compactness, among other factors, which is afforded by apparatus in which the plasma or arc chamber is adjacent the substrate chamber.
It is with respect to these and other considerations that the present improvements have been needed.